*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style: none;
}
body {
    background-color: #f5f5f5;
}
a {
    width: 100%;
    height: 100%;
    color: #252222;
    display: block;
    text-decoration: none;
}
/* 导航条 */
nav {
    height: 50px;
    /* background-color: #96d4f5e1; */
    line-height: 50px;
}
/* 宽 */
.navigation{
    width: 1000px;
    margin: 20px auto;
}
nav ul {
    display: flex;
    position: relative;
    height: 100%;
    justify-content: space-between;
}

nav ul li {
    width: 50px;
    position: absolute;

}

nav ul li a {
    position: relative;
    width: 200px;
    height: 100%;
    transition: all 0.3s;
    color: #efeaea;
    font-size: 18px;
    font-weight: 700;

}

nav ul li a::before {
    content: "";
    position: absolute;
    width: 80px;
    height: 2px;
    background-color: #efeaea;
    left: -2px;
    bottom: 5px;
    z-index: 1;
    display: none;
    transition: all 0.3s;
}

nav ul li a:hover {
    transform: translateY(-4px);
}

nav ul li a:hover::before {
    display: block;
}

nav ul li:nth-child(1) {
    left: 50px;
}

nav ul li:nth-child(2) {
    left: 350px;
}

nav ul li:nth-child(3) {
    right: 350px;
}
nav ul li:nth-child(4) {
    right: 100px;
}

/* 头部 */
.top{
    display: flex;
    background-color: #ffffff;
    height: 350px;
    margin-top: 30px;
    border-radius: 18px;
    overflow: hidden;
    transition: all 0.3s;
    box-shadow: 5px 5px 8px #2d2b2b8b;
}
.top:hover img{
    transform: scale(1.1);
}
.top img{
    width: 100%;
     height: 100%;
     transition: all 0.3s;
}
.pic{
    flex: 50%;
    overflow: hidden;
}

.text{
    flex: 50%;
    padding: 20px 30px;
}
.text h2{
    font-size: 45px;
    font-weight: 700;
    margin-bottom: 30px;
}
.text p{
    font-size: 16px;
    margin-bottom: 10px;
    color: #888585;
}
.text a{
    text-decoration: none;
    font-size: 18px;
    color: white;
    /* font-weight: 700; */
    line-height: 50px;
}
button{
    width: 200px;
    height: 50px;
    padding: 2px;
    margin-top: 30px;
    border-radius: 30px;
    background-color: rgb(102, 225, 102);
    border: none;
}
button:hover{
     /* 鼠标悬停变手型 */
     cursor: pointer;
     /* 鼠标悬停会变化大小 */
     transform: scale(1.1);
}

/* 课程介绍 */
#introduce{
    background-color: #fff;
    padding: 30px 30px;
    padding-bottom: 40px;
    border-radius: 18px;
    box-shadow: 5px 5px 8px #2d2b2b8b;
    line-height: 20px;
}
h4 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 10px;

}
.content p {
    line-height: 30px;
    text-indent: 25px;
    letter-spacing: 0.5px;
    color: rgb(87, 86, 86);
}

/* 章节目录 */
#catalogue{
    background-color: #fff;
    padding: 30px 30px;
    padding-bottom: 40px;
    border-radius: 18px;
    box-shadow: 5px 5px 8px #2d2b2b8b;
    line-height: 20px;
}
.passage{
    margin-top: 10px;
}
.L{
    text-indent: 30px;
    margin-left: 15px;
    margin-bottom: 8px;
    letter-spacing: 2px;
    font-weight: 400;
    font-size: 18px;
    color: rgb(129, 125, 125);
}
#catalogue ul {
    margin-bottom: 20px;
    padding-left: 40px;
}
#catalogue span{
    font-size: 21px;
     letter-spacing: 2px;
}

/* 教师资历 */
#teacher {
    padding: 30px;
    background-color: #ffffff;
    border-radius: 18px;
    box-shadow: 5px 5px 8px #2d2b2b8b;
}
.box {
    display: flex;
    flex-wrap: nowrap;
    margin-top: 10px;
    
}
.photos{
    width: 180px;
    height: 180px;
    overflow: hidden;
    margin-right: 20px;
}
.photos img{
    width: 100%;
    height: 120%;
    transition: all 0.2s;
}
.word{
    flex: 1;
    font-size: 16px;
    letter-spacing: 1px;
    line-height: 35px;
    text-indent: 26px;
}
#teacher:hover img {
    transform: scale(1.1);
}
